title: "Emergency Medicine Rotation Deep Dive"
Emergency Medicine Rotation Deep Dive
This page consolidates key ED concepts from across the Critical Care curriculum. Use it as your reference when starting your Emergency Department rotation.
1. ED Workflow
Triage
Australasian Triage Scale (ATS):
| Category | Max Wait | Examples |
|---|---|---|
| 1 | Immediate | Cardiac arrest, major trauma, severe respiratory distress |
| 2 | 10 min | Chest pain, severe pain, altered LOC |
| 3 | 30 min | Moderate pain, vomiting, mild respiratory distress |
| 4 | 60 min | Minor trauma, mild pain |
| 5 | 120 min | Admin, chronic issues, scripts |
Triage is a dynamic process. Patients can deteriorate - reassess while waiting. A "category 4" abdo pain can become a category 1 ruptured AAA.
The Primary Survey
- A - Airway - Patent? Obstruction? Can they speak?
- B - Breathing - RR, SpO2, work of breathing, air entry, chest wall
- C - Circulation - HR, BP, cap refill, skin colour, bleeding
- D - Disability - GCS, pupils, glucose, lateralising signs
- E - Exposure - Temperature, rash, injuries (fully undress)
Treat problems as you find them. The primary survey is not just assessment - intervene immediately at each step. Airway problem? Secure airway before moving to B.
2. Resuscitation
Cardiac Arrest - ALS Algorithm
See the [[advanced-life-support]] wiki for the full algorithm.
Shockable rhythms: VF, pVT → Defibrillate! Non-shockable rhythms: Asystole, PEA → CPR + adrenaline
See also: [[shockable-rhythms]], [[non-shockable-rhythms]], [[adrenaline]]
H's:
- Hypoxia → give oxygen, secure airway
- Hypovolaemia → give fluids, control bleeding
- Hypo/Hyperkalaemia → treat with calcium, insulin/glucose
- Hypothermia → warm to 32°C before declaring death
T's:
- Tension pneumothorax → needle decompression, then chest drain
- Tamponade (cardiac) → pericardiocentesis
- Toxins → consider antidotes (naloxone, digoxin Fab, intralipid)
- Thrombosis (PE or coronary) → thrombolysis or PCI if suspected
See also: [[hypovolaemic-shock]], [[hyperkalaemia]], [[pneumothorax]], [[pulmonary-embolism]]
Post-Arrest Care
Targeted Temperature Management:
- Actively prevent fever (≤37.5°C) in comatose survivors after ROSC (continue for at least 72 hours)
- If mildly hypothermic after ROSC, do not actively warm to normothermia
- Coronary angiography if STEMI or suspected cardiac cause
Source: ANZCOR post-resuscitation care guidance; local ICU protocol.
3. Chest Pain
See the [[chest-pain-approach]] wiki for a systematic approach.
Risk Stratification
High-risk features requiring urgent workup:
- Pain at rest or prolonged (>20 min)
- Diaphoresis
- Radiation to arm/jaw
- Associated dyspnoea
- Known CAD
- Dynamic ECG changes
- Elevated troponin
The ECG in ACS
See the [[ecg-acs]] wiki for detailed ECG patterns.
| Pattern | Diagnosis | Action |
|---|---|---|
| ST elevation (≥2mm precordial, ≥1mm limb) | STEMI | Cath lab <90 min |
| ST depression, T inversion | NSTEMI/UA | Risk stratify, anticoagulate |
| New LBBB | May mask occlusion MI (use Sgarbossa/modified Sgarbossa + clinical picture) | Urgent cardiology; activate cath lab if occlusion suspected |
| Wellens' pattern | Proximal LAD lesion | High risk, early angio |
| de Winter T waves | LAD occlusion | Treat as STEMI equivalent |
Posterior STEMI: Looks like ST depression V1-V3. Do posterior leads (V7-V9) if suspicious. Missed posterior MI = missed cath lab.
STEMI Management
- M - Morphine (if pain uncontrolled)
- O - Oxygen (only if SpO2 <94%)
- N - Nitrates (sublingual GTN, avoid if RV infarct/hypotensive)
- A - Aspirin 300mg
- B - Beta-blocker (oral, once stable)
Plus: P2Y12 inhibitor (clopidogrel/ticagrelor), anticoagulation, reperfusion
4. Dyspnoea
Differentiation
| Condition | Key Features | Investigations |
|---|---|---|
| Asthma/COPD | Wheeze, prolonged expiration, history | Peak flow, ABG |
| Pneumonia | Fever, cough, consolidation signs | CXR, cultures |
| PE | Pleuritic pain, risk factors, tachycardia | D-dimer, CTPA |
| APO | Orthopnoea, crackles, JVP elevated | BNP, CXR, echo |
| Pneumothorax | Sudden onset, reduced air entry, resonant | CXR |
| Anaphylaxis | Urticaria, wheeze, hypotension, trigger | Clinical |
Oxygen Therapy
Target SpO2:
- Most patients: 94-98%
- COPD/CO2 retainers: 88-92%
Don't withhold oxygen in critically unwell patients - hypoxia kills faster than hypercapnia.
Source: COPD-X Plan; local oxygen therapy guideline.
Acute Severe Asthma
Life-threatening features:
- Silent chest
- Cyanosis
- Poor respiratory effort
- Bradycardia, hypotension
- Exhaustion, confusion
- SpO2 <92%, PaO2 <8 kPa
- Normal or rising PaCO2
A "normal" CO2 in acute asthma is dangerous - they should be hyperventilating!
Source: Australian Asthma Handbook; local ED asthma guideline.
5. Shock Recognition
Clinical Signs
Signs of shock:
- Tachycardia (early compensatory)
- Hypotension (late - indicates decompensation)
- Cool, mottled peripheries (hypovolaemic/cardiogenic)
- Warm, vasodilated (distributive)
- Altered mental state
- Oliguria (<0.5 mL/kg/hr)
- Elevated lactate
Source: CC Bible; local ED/ICU shock recognition.
The 4 Types
| Type | Mechanism | Think Of |
|---|---|---|
| Hypovolaemic | Not enough volume | Bleeding, dehydration, burns |
| Cardiogenic | Pump failure | MI, arrhythmia, valve failure |
| Distributive | Vasodilation | Sepsis, anaphylaxis, neurogenic |
| Obstructive | Blocked flow | PE, tamponade, tension pneumo |
Fluid Resuscitation
Crystalloid first: Hartmann's or normal saline 500-1000mL bolus, reassess.
Blood products if:
- Haemorrhagic shock
- Hb <70 (or <80 in ACS)
- Massive transfusion protocol activated
Source: CC Bible; local shock + transfusion protocols.
6. Trauma
Primary Survey in Trauma
- A - Airway with C-spine control
- B - Breathing
- C - Circulation with haemorrhage control
- D - Disability
- E - Exposure and environment
Adjuncts: ECG, IDC, OGT, X-rays (CXR, pelvis, FAST)
Life-Threatening Chest Injuries
Find and fix immediately:
- Tension pneumothorax → Needle decompress, then ICC
- Massive haemothorax → ICC + blood, likely needs thoracotomy
- Cardiac tamponade → Pericardiocentesis or thoracotomy
- Open pneumothorax → 3-sided dressing, then ICC
- Flail chest → Analgesia, ventilatory support
FAST Exam
Q: FAST views (4) for free fluid: [], [], [], []. A: RUQ (hepatorenal/Morison's pouch); LUQ (splenorenal); pelvis (bladder); subxiphoid (pericardial)
Q: Unstable trauma + positive FAST → [___]. A: immediate laparotomy (theatre)
C-Spine Clearance
NEXUS Criteria (all must be met to clear without imaging):
- No midline cervical tenderness
- No focal neurological deficit
- Normal alertness
- No intoxication
- No painful distracting injury
If ANY criteria not met → Image the C-spine
7. Acute Stroke & SAH Imaging
Non-contrast CT brain is the workhorse investigation in acute stroke - fast, accessible, excellent for excluding haemorrhage. Perform within 60 minutes of ED arrival for suspected stroke.
Source: Dr. Sally Aesa radiology lecture; stroke imaging guidelines.
Systematic CT Brain Review
- Blood - Look for hyperdense areas (fresh blood is WHITE/bright)
- Brain parenchyma - Symmetry, sulci effaced, grey-white differentiation, midline shift
- Bones/skull - Fractures in bone window
- CSF spaces - Ventricle size, hydrocephalus, cisterns
- Mass effect - Midline shift >5mm, herniation
CT density basics:
- Bright (hyperdense) = blood, bone, calcification
- Dark (hypodense) = air, fat, oedema, CSF
- Grey = normal brain parenchyma
Ischemic Stroke Imaging
Early CT Signs
| Finding | Appearance | Significance |
|---|---|---|
| Hyperdense vessel sign | Bright artery (clot within vessel) | Acute large vessel occlusion |
| Loss of insular ribbon | Loss of grey-white differentiation in insula | Early MCA territory stroke |
| Loss of grey-white | Poor differentiation, hypodense cortex | Developing infarct |
| Effaced sulci | Loss of normal grooves | Cerebral oedema |
| Midline shift | Falx cerebri displaced >5mm | Mass effect, herniation risk |
The insular ribbon is your friend. Loss of grey-white differentiation in the insula (posterior to Sylvian fissure) is an early and sensitive sign of MCA territory ischemia. Check it first when looking for acute stroke.
Source: Dr. Sally Aesa lecture.
Normal non-contrast CT does not exclude early ischemic stroke. Early changes may be subtle in the first 6 hours. If clinical suspicion high, proceed with CT angiography and consider MRI.
CT Angiography (CTA)
Indications for urgent CTA in suspected stroke:
- Clinical stroke syndrome present
- No haemorrhage on non-contrast CT
- Within thrombolysis/thrombectomy window (up to 24h with CT perfusion)
- Assesses circle of Willis for large vessel occlusion
Source: Local stroke protocol; Dr. Sally Aesa lecture.
What CTA shows:
- Large vessel occlusion (ICA, MCA, basilar)
- Carotid stenosis or dissection
- Aneurysms (if SAH suspected)
MRI in Stroke
Acute stroke MRI: DWI shows Bright signal (restricted diffusion) and ADC shows Dark signal (confirms true restriction). Bright DWI + Dark ADC = true acute ischaemic stroke. FLAIR and T2 become bright later in the subacute phase (vasogenic oedema).
DWI/ADC mismatch is the gold standard for diagnosing acute stroke on MRI. DWI can be bright in many conditions, but when paired with LOW ADC (dark), this confirms true diffusion restriction from cytotoxic oedema.
CT Perfusion
Used to assess salvageable brain in extended window (6-24 hours):
- Infarct core - Decreased cerebral blood volume (brain already dead)
- Penumbra - Increased mean transit time with preserved volume (threatened but salvageable)
- Guides decision for mechanical thrombectomy beyond 6 hours
Subarachnoid Haemorrhage (SAH)
SAH on CT:
- Fresh blood is bright (hyperdense) in CSF spaces
- Classic appearance: blood filling basal cisterns in "star pattern"
- Sensitivity ~95% if CT done within 6 hours of headache onset
Source: Dr. Sally Aesa lecture; SAH imaging guidelines.
SAH Review Areas (Where Blood Pools)
- Interpeduncular cistern - Normally dark triangle, bright if SAH
- Sylvian fissures - Bilateral wispy hyperdensity
- Cortical sulci (convexities) - Linear bright blood along brain surface
- Posterior horns of lateral ventricles - Blood pools here when supine
- Basal cisterns - Star-like pattern of blood
If CT is negative but SAH still suspected clinically, perform LP 12 hours after headache onset to look for xanthochromia. CT sensitivity drops to ~50% after 1 week.
SAH Imaging Pathway
Thunderclap headache pathway:
- Urgent non-contrast CT brain - look for blood
- If SAH detected → CT angiogram (CTA) of circle of Willis to find aneurysm
- If CT negative but high suspicion → LP at 12 hours for xanthochromia
- If SAH confirmed → Discuss with neurosurgery for catheter angiography ± coiling/clipping
Source: ACEM diagnostic imaging guidelines; Dr. Sally Aesa lecture.
Common aneurysm locations:
- Anterior communicating artery (AComm) - most common
- Posterior communicating artery (PComm)
- MCA bifurcation
- Basilar tip
Stroke Mimics
Not everything that looks like stroke is stroke!
CT brain with contrast can reveal:
- Multifocal enhancing masses → Cerebral metastases
- Ring-enhancing lesion → Abscess (if febrile)
- Hemorrhagic transformation → Blood within infarct
- Space-occupying lesion → Tumour causing focal neurology
Practice Questions
What is the most appropriate next step?
8. Common ED Presentations
Abdominal Pain
- Peritonism (guarding, rigidity, rebound)
- Distension with absent bowel sounds
- Haemodynamic instability
- Fever with localised signs
- Free air on CXR
- Pulsatile abdominal mass (AAA)
Syncope
High-risk features (need admission):
- Exertional syncope
- Syncope while supine
- Associated chest pain or palpitations
- Family history of sudden death
- Abnormal ECG (long QT, Brugada, WPW)
- Structural heart disease
- New neurological signs
Headache
Headache red flags:
- "Worst headache of my life" → SAH
- Fever + neck stiffness → Meningitis
- Papilloedema → Raised ICP
- New headache >50 years → GCA, malignancy
- Focal neurology → Mass, stroke
- Thunderclap onset → SAH, CVT, dissection
9. Procedures
Needle Thoracostomy
Tension pneumothorax - immediate decompression:
- Use a long, large-bore cannula (ideally ~8 cm, 12–14G)
- Sites: 2nd intercostal space at/just lateral to mid-clavicular line, or 4th/5th intercostal space just anterior to the mid-axillary line
- Insert cannula, remove needle
- Expect rush of air
- Follow with definitive ICC
Source: ATLS / local trauma guideline.
Central Line
Sites:
- Internal jugular (ultrasound guided - preferred)
- Subclavian (highest pneumothorax risk)
- Femoral (easiest but highest infection risk)
Confirm position: CXR before use (except emergency)
10. Disposition
Admission Criteria
Consider admission if:
- Unstable vital signs
- Requiring ongoing IV therapy
- Unable to maintain hydration/nutrition
- Requires monitoring for deterioration
- Unable to mobilise/care for self
- Concerning diagnosis requiring workup
- Inadequate social supports
The "2am test": Would you be comfortable with this patient at home at 2am? If not, admit.
11. Practice Questions
What is the door-to-balloon time target?
What diagnosis must be excluded?
Status Epilepticus: Immediate Pharmacology
First-line seizure control: midazolam 5-10 mg IV.
Source: ANZCOR; local ED seizure pathway.
Second-line: phenytoin 18 mg/kg IV over 30 minutes after benzodiazepine.
Source: eTG; local ED seizure pathway.
Q: Alternative second-line options: levetiracetam [] mg/kg IV (max 4.5 g) or valproate [] mg/kg IV over 15 minutes. A: 60; 40
IV phenytoin maximum infusion rate is 50 mg/min; monitor ECG and BP and avoid extravasation (fosphenytoin if available).
Refractory status epilepticus: RSI and ICU sedation. Typical regimens include propofol 1-2 mg/kg bolus then 1-5 mg/kg/hr infusion or midazolam infusion 0.1-0.4 mg/kg/hr (local protocol).
Source: eTG; local ED seizure pathway.
Treat hypoglycaemia immediately with 50 mL of 50% glucose.
Source: local hypoglycaemia protocol.
Source: CC Bible (seizure control section).
What is the next step?
What is the next step?
What is the next investigation?
What is the concern?
Warfarin toxicity without bleeding (INR >8): hold warfarin + vitamin K 1-2 mg PO; recheck INR next day.
Source: Local ED anticoagulation guideline.
What is the management?
12. Tubes & Lines on Chest X-Ray
CXR is a 2D projection - we say the tip "projects over" anatomical structures, but always correlate clinically (is the NGT flushing? Are sats OK?). Cannot definitively confirm 3D position without CT.
Source: Dr. Sally Aesa lecture on tubes and lines imaging.
Endotracheal Tube (ETT)
Ideal position:
- Tip 5 cm above carina (±2 cm acceptable)
- Measured with patient in neutral neck position
ETT malposition risks:
- Too low → endobronchial intubation (usually right main bronchus) → one-lung ventilation, contralateral lung collapse
- Too high → ineffective ventilation, risk of extubation with neck flexion
Paediatric tip position: T2-T4 vertebral level
Carina is your landmark - bifurcation of trachea into right and left main bronchi. Count down from clavicles to find it.
Nasogastric Tube (NGT)
Ideal position:
- Course should bisect the carina (oesophagus passes posterior to carina)
- Tip well below gastro-oesophageal junction
- All side holes below GOJ (if feeding - risk aspiration if in oesophagus)
NGT malposition - bronchial placement:
- If tube "kicks off to the side" at the carina → likely in bronchus (right main bronchus most common)
- Never feed through a bronchially placed NGT → aspiration pneumonitis
NGT types:
- Some have weighted radio-opaque tip
- Variable side holes (marked by breaks in radio-dense line)
- Calibre varies by indication
Central Venous Catheters
Ideal tip position: Atriocaval junction (junction of SVC and right atrium)
- Also acceptable: upper right atrium or SVC
Insertion sites:
- Internal jugular vein (most common)
- Subclavian vein
- Femoral vein (not ideal for long-term)
PICC lines: Inserted via arm (cephalic or basilic veins) → same target (atriocaval junction)
CVC malposition complications:
- Coiled/kinked catheter → ineffective drug delivery, thrombosis risk, vessel damage
- Tip too high (in IJV/brachiocephalic) → ineffective infusion
- Tip heading cranially (e.g., up towards head) → resite required
Portacath identification: Metallic hub with central bubble (where gripper needle accesses)
Vascath (dialysis catheter): Two separate lumens visible on CXR (for in/out flow)
Chest Drains (Intercostal Catheters)
Indication-based positioning:
- Pneumothorax → air rises → drain apex (apical placement)
- Pleural effusion → fluid settles → drain base (basal placement)
- Loculated fluid → drain within the pocket (requires imaging guidance, often CT)
Check side holes! All side holes must be within the thoracic cavity. Side holes outside chest → ineffective drainage + risk subcutaneous emphysema (for pneumothorax).
Chest drain in subcutaneous tissue or abdominal cavity → remove and resite. Do not advance.
Cardiac Devices
Pacemaker vs ICD (defibrillator):
- Pacemaker → thin wires throughout
- ICD → wires have thickened sections (shock coils)
Loop recorder: Looks like "USB stick" in subcutaneous pocket - records cardiac rhythm
EVAR (endovascular aortic repair): Cage-like structure following aortic contour
Systematic Approach to Busy CXR
When multiple tubes/lines present:
- Check each line individually in turn
- ETT position (5cm above carina?)
- NGT course (bisects carina? Tip below diaphragm?)
- Central line tip (atriocaval junction?)
- Chest drain (side holes in? Tip in correct location?)
- Cardiac devices (identify type)
- ECG leads (don't mistake for tubes!)
Common scenario: Post-intubation CXR shows correctly positioned ETT but misplaced NGT in right lower lobe. Always check every line - one correct doesn't mean all correct.
Source: Dr. Sally Aesa lecture, North Shore Hospital radiology teaching.
Emergency Medicine Study Checklist
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